Ground clamp



Nov. 22,l 1938-. N. G. HAYES r 2,137,840

' GROUND CLAMP v Filed Feb. s, 1957 /3 /7 mum? j Mmmm '-lNvENToR Nell ages,

Patented Nov. 22, 1938 UNITED STATES eA'iEnr OFFICE GRO-UND CLAMP Neil G. Hayes, Bridgeport, Conn. Application February 8, 1937, Serial No. 124,590

2 Claims.

This invention relates to ground clamps, or connectors for grounding a conduit and a conductor in an electrical system to a water or other grounding pipe.

Previous ground clamps of this kind have comprised a metal xture securable to the grounding pipe, a metal device for having connected thereto `a conductor and a conduit oi the electrical system to be grounded, and means for coupling the fixture and the device so as to secure them together in any one of several angular adjustments between the saine. v

An object of the invention is to provide such a ground clamp, but one comprising principally two simplarugged and easily finished metal parts, as castings, one to constitute the fixture and the other to constitute the device, but nevertheless, a clamp so constructed that a rounding of the pipe is Seized in a curved part of the fix- Ature, and this by tightening of a single screw to force an end of that screw directly against the pipe.

A feature of the new ground clamp is the inclusion of a pipe-embracing fixture having substantially the shape of an oval open at one side. Such oval provides, `at one end and at its closed side near that end, a curved claw for cradling therein apart of the rounding of a pipe. The pipe-clamping screw is placed on the iiXture so as to pass through an end portion oi the oval opposite the claw and to be directed toward a point on the claw intermediate the ends thereof. Then it is possible to hook the claw around the pipe preparatory to tightening the screw, there- 3:, `by to facilitate connection and easy securement of` the fixture to the pipe.

Another feature of the invention is the attachment, to the closed side of the oval, and at a point in that side nearer to the screw than to .m the claw, of the device for receiving the conductor and conduit to be grounded. At this part of the xture the bulk of metal is considerable so as to give proper strength to the oval. This bulk of metal makes it practicable to have the .15 means for attaching the device to the iixture include merely two flat table-like portions one at the exterior of the iixture, and the other on the bottomof the device, with both ci these tables in direct `face engagement, additional to a coupling screw for the fixture and the device and passing through both table-like portions. Preferably, this screw is directed toward a point intermediate the ends of the opening in the open side of the oval, because then, with the oval shaped for maximum strength and lightness, and

. yet designed so as properly to be clamped to any one oi a Vnumber oli pipes of different diameters, the coupling screw is so located as not to interfere with either` the pipe-clamping screw or a pipecradled in the xture and clamped therein bydirectly applied thrust of the pipe-clamping screw, even when the pipeis the largest one of the several sizes of pipe for which the xture is designed. V

Still another feature of the invention is vthe provision of projections arranged within and spaced along the length of the curved claw and having their tops so disposed relative to the general curvature of the claw that for each of a plurality of pipes of different diameters a special plurality of said projections engages the rounding of the pipe when the pipe-clamping screw is tightened.

Various other objects and advantages will hereinafter appear.

In the accompanying drawing- Figure l is an elevational view showing in iull lines a grounding pipe and a tting according to the invention applied thereto,this View indicating, in broken lines, various of the many possible angular adjustments of the device for receiving a conductor and, conduit to be grounded.

Fig. 2 is also an elevational view, but one lookingtoward the left in Fig. 1, and partially broken away and partially in section.

Fig. 3 is a top plan view of the tting as shown in Fig. 1, with the grounding pipe shown in sec-V tion.

Fig. 4; is a View similar to Fig. 1, but-showing a modication.

Fig. 5 is a` view similar to Fig. 2, showing said v modification.

Fig. 6 is an elevational view oi.` said modification as shown in full lines in Fig. 4, but showing certain parts in section according to the line B of Fig. 5.

In the form of the invention illustrated herein, which is the form at present preferred, thexture It, which is the element of the ground tting to loe clamped to a grounding pipe or rod, such, for instance, as the water pipe Il, is coinprised oi a single casting I2 and a clamp screw As shown best in Fig. 3, the fixture I is of substantially the shape of an oval open at one. side, thereby to provide a curved claw I4 for cradling therein a part of the rounding of the pipe II. The screw I3 passes through a tapped hole in the end portion I of the oval opposite the claw. `This hole is directed toward a point on the claw intermediate the ends thereof, so that when the screw is tightened against a pipe in the claw, the thrust of the screw will be such as to hold the latter to retenion by the claw. The head I3 of the screw is shown as hexagonal for the application of a wrench, and also kerfed, to allow of the use of a screw driver, in tightening up the screw.

The claw curvature merges with a curvature down along the side I6 of the oval, and this, among other advantages which will be later mentioned, gives maximum strength and lightness to the fixture as a Whole.

The curved claw I4 allows the end of the xture carrying the same to be hooked-over the pipe II preparatory to tightening up the screw I3. 'I'his facilitates quick and easy attachment of the fixture to the pipe, to a degree suicient to prevent accidental loss of the xture from or unintended slipping of the same along or around the pipe, by a preliminary tightening of the screw I3. The fixture I may then be shifted if and as required to give the same exactly the desired position on the pipe II, whereupon the screwv I3 may be fully tightened up, and locked as thus tightened, for which purpose a clamp nut I1 is preferably carried by the screw as shown.

In order to insure that the curved claw I4 may be able to take pipes of different diameters, but will always have not only a hook engagement with, but a definite cradling hold on the pipe therein, the claw is provided at its inner face with a plurality of spaced projections. The projections shown, marked I8, I9, 20, 2|, 22 and 23, are so spaced along the length of the claw, and the tops of the projections are so arranged, that one projection, as thev projection I9, intermediate two other projections, as the projections IB and 20, has its top located to lie outside a circle defined by the tops of the two projections last-mentioned when such circle is so drawn as to have the projections last-mentioned exterior` thereto. The various projections, also, it will be noted, are shown as irregularly spaced along the curved claw. By such an arrangement, insurance is had that a pipe of one diameter will be cradled Within the curved claw on a plurality of fairly widely spaced projections, and a pipe of another diameter will be cradled within the claw on another plurality of fairly widely spaced projections; and at the same time, in either case, the pipe will be held in the claw so that a prolongation of the center line of the screw I3 will substantially intersect the axis of the pipe. Such a condition is illustrated in Fig. 3 in connection with the pipe I I, where the same is engaged by the screw I 3 as described, and at the same time is cradled within the curved claw on the projections I9 and 2|. A smaller pipe, for instance, would be thus cradled on the projections I9 and 20. Similarly, a larger pipe than the pipe I I would be cradled on the projections I9 and 2U, while a still larger pipe would be cradled on the projections I9 and 22, and a yet larger pipe on the projections I8 and 23.

Thus a curved claw may be employed, for true hook engagement with the grounding pipe, and at the same time this claw is adapted to receive pipes of widely different diameters, but always in away to avoid having merely a single-line contact with the pipe where the latter is of a size such that its rounding is of less degree of curvature than the inner face of the claw.

'Ihe merging of the curvature of the claw with the curvature down along the side I6 of the oval,

one of the advantages of which has already been mentioned, also coacts with the projections on the inner face of the curved claw to make it possible to provide a fixture I0 which is only very little larger than the largest pipe to Which the xture is intended to be secured. Note in this connection, the concavity 24 which is provided in the form of the invention shown, and which is placed to the left of the projection 23 of the curved claw I4. This concavity acts as a receptor for the rounding of a pipe of very large diameter compared with the pipe II, when this very large pipe is cradled in the curved claw on the projections I8 and 23.

The concavity 24 is down along the side I6 of the oval close to the clamp screw I3, and so coacts with the generally strengthening curvature of this oval side I6 to provide a part 25 of the oval which, Without being of excessive weight, is of adequate bulk to permit the tting to have a very simple means for properly coupling, to the xture I0, the device for receiving the conductor and conduit to be grounded to the pile II, In the form of the invention shown in Figs. l to 3, this device is indicated generally by the reference character 26. In the embodiment illustrated in Figs. 4 and 6, this device is indicated generally at 26.

The attaching means for securing the device 26 or 26 to the fixture I0, and for adjusting the former angularly as required relatively to the latter, for instance, as shown in broken lines in Figs. 1 and 4, comprises merely a flat table-like portion 21 at the exterior of the part 25 of the xture I il, a similar table-like portion at the bottom of the device 26 or 26 and placed in direct face engagement with the table-like portion 21 on the xture, and a screw 28 having, like the pipe-clamping screw I3, a kerfed bolt head 28'. As shown in Figs. 2 and 5, this screw, passed through a cylindrical hole in the device 26 or 26', is in threaded engagement with a tapped hole through the part 25 of the fixture IU.

Referring more particularly to the device 26 of Figs. 1, 2 and 3, this is shown as consisting of a single part comprising a threaded nipple 26a and a leaf-extension 26h. On the bottom of the extension 2Gb, is the flat table-like portion aforesaid which is placed in direct face engagement with the flat table-like portion 21 on the iixture IIJ, and through this extension 2Gb is passed the screw 23 which couples the device 2B and the ixture Il). For strengthening purposes, webs or fillets 28C may be provided, but these should not obstruct free access to the extension 28h.

The device 26 is designed for use with a pipe conduit 29 to be grounded, and this nipple is threaded for taking a threaded end of the conduit. In the present case, the nipple is shown as being interiorly threaded, but it will be understood that it may be exteriorly threaded, or both interiorly and exteriorly threaded, in which last case a nipple of one size may accommodate, without the use of reducers. two sizes of pipe,

To complete grounding of the electrical system, in the form of the invention shown in Figs. 1, ,2

and 3, a grounding wire 3U carried in the con- 29 and the wire 3| are grounded through the xture Ill to the grounding pipe I I. In the structure illustrated, a split washer 32 is interposed between the lug 3I and the head of the screw 28, forlocking the screw to its finally tightened position.

The flat table-like portions which are in direct face engagement between the fixture I and the device 25 are easily wiped clean if dirty, and so there can be no accidental insulation between these parts. The upper face of the extension 26a of the device 26 need not be iinished to a smooth surface, or otherwise specially formed to facilitate cleaning, as the grounding current will pass from the lug 3I to the washer 32 and to the head of the screw 28, and through the screw to the fixture I0 and thence to the grounding pipe I I.

When the parts are nally all coupled and assembled as described, even relative to a grounding pipe much larger than the pipe II, as a grounding pipe so large that a part of its rounding extends well into the concavity 24, it will be noted that the coupling screw 28, when fully tightened up, does not protrude far enough into this concavity to limit the capacity of the xture I0 to a grounding pipe smaller than permitted by the concavity with the screw 28 retracted beyond the concavity. On the other hand, the thickness of the part 25 of the fixture in the direction of advance of the screw 28 gives the latter ample thread engagement with the tapped hole through the part 25; and this is another advantage resulting from the shaping of the fixture ID to provide, in connection with the curved claw I4, a side I6 having a curvature merging with the curvature of the claw in a way to give i the fixture maximum lightness yet adequate strength all over.

Referring now to the modification shown in Figs. 4, and 6, and particularly to the device 26', the substitution of which, for the device 26 of Figs. 1, 2 and 3, constitutes such modification:

The device 26 is adapted particularly for use when the grounding wire is a wire 33 covered by a flexible metal conduit 34, so that both this wire and this conduit are the ones to be grounded.

The device 26 includes a cylindrical neck 26a upstanding from one end of a leaf-extension 26h'. In order to secure the conduit 34 in and ground the saine to the neck, the latter is provided with a set screw 35. The leaf-extension 26h has on its bottom a at table-portion like that of the device 26, and through this leaf-extension is sent a screw 28 as in the case of the device last-mentioned.

Thus, the attachment of the device 26' to the xture IU, and a setting of the device to the angle desired relative to the pipe Il, is obtained as already described in connection with the device 26,

However, the upper face of the leaf-extension 26h of the device 26 is upwardly peripherally cupped and carries a central boss 26o' surrounding the opening for the screw 28. As shown, this boss is of somewhat less height than the rim of the cup. Between the boss and the cup rim there is an annular groove 26d. Sleeved on the upper end of the screw 28 is a disk 36. The groove 26d is of such a depth, relative to the height of the boss and to the thickness of the grounding wire 33, that when a bared end length 33 of the latter is curled and laid in the groove as illustrated in Figs. 5 and 6, and the screw l28 is tightened to force the disk 36 into the cup, the disk will squeeze the curl of the wire down tight in the groove and tight against the lower face of the disk, before the disk reaches the top of the boss 26e. As shown at 31, a split washer is desirably interposed between the disk 36 and the head of the screw, to lock the screw to its finally tightened position.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim:

1. A. ground fitting comprising a pipe-engaging fixture of substantially C-shape and having a pipe-engaging surface along the inner face of the curved end and one side thereof, said surface comprising pipe-engaging projections spaced along the length of the surface and having their tops so located within the clamp that the tops of the first projection and second projection define a circle corresponding to one pipe diameter and the top of a projection between the first and second projections and the top of a projection beyond one of said rst and second projections dene a circle corresponding to another pipe diameter, said fixture having a tapped hole in the end portion opposite the pipe-engaging portion; a clamping screw in said hole; a device on the xture adjacent the clamping screw for receiving the grounding conductor and conduit; and means for securing and angularly adjusting the device on the tting.

2. A ground fitting comprising a pipe-engaging fixture of substantially C-shape and having a pipe-engaging surface along the inner face of the curved end and one side thereof, said surface comprising pipe-engaging projections irregularly spaced along the length of said surface; a projection intermediate two other projections having its top located to lie outside a circle dened by the top of the two projections last-mentioned when said circle is so drawn as to have the projections last-named exterior thereto; and means for securing a grounding conductor or conduit thereto.

NEIL G. HAYES. 

